Variable pitch airscrew



c. DAscANlo.

VARIABLE P11011 Anscnnw Filed out. 19. 1939 III/Ilz VI/II l [ifa filippi/"11,

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Patented Dec. 15,151942 UNITED f sTA'I'EsY V1?:115N1' oFF-ICE comme mamme, rin, muy; mica in un Alien Property Custodian Application October 19, 1939, Serial No. 399,213

-f In Italy October 31, 1938 8 Claims. (Cl. T10-163) vide means for automatically adjusting the pitch of the propeller as soon as the same exceeds a predetermined maximum number of revolutions. Furthermore, the propeller of the present invention is equipped with a supplementary control' means, which in addition to serving as an emergency control, is' used for effecting a full feathering arrangement of the propeller blades. v

The invention will bebest understood from the following description and from the accompanying drawing which shows by way of example one embodiment of the invention.

In the drawing:

Fig. l is a section through the upper portion in a plane passing through the -engine axis and the axis of a blade of the propeller.

Fis. l is a section through the lower portion in a plane passing through the engine axis and through the axis ofan endless screw which adlusts a propeller blade.

F18. 2 shows a section of the control taken in a plane normal to the engine axis. and,

lFig. 3 shows an example of electric wiring diagram.

vAccording to the embodiment illustrated, the invention comprises a hub constituted by the body I to which the propeller blades 2 are anchored, with the base of which latter is integral a sector of 'a worm gear 3 geared withlan endless screw 4 supported by the said hub. A

A gearing drives the endless screws 4; igt-iscomposed of gears I keyed to the axes of the end-v less screws 4, said gears meshing with a 'gear t loosely mounted on the driving shaft. Co-axial andintegralwiththegeariandthereforeloose.

upon the driving shaft, there is. a 'gear Il. A gear Il ofthesamesizeasgear lliskeyedto the driving shaft Y With the gears Il and Il there are respectivelyinmeshtwosetsofplanetarygearslandl of like diameter, both of which are in mesh with an internally toothed rim l. The shafts carrying the planetary gears t are supported Vby a circular plate I2 whichl is integral with ythecasing, whereas the shaftscarryingthe planetary gears 1 are supported by a dish-shaped plate Il rotatably mounted on the' circumference of the stationary plate l2. The plate. is adapted to be rotated from the outside by means of a pinion I4 which meshes with the gear teeth I5 on the outer circumference of the rim of the dishshaped plate Il.

Due to the connection between the two sets lof planetary gears, an angular displacement of the plate I3 causes a rotation of the integral gears 6 and I0 with respect to the gear Il, and therefore the endless screws 4 effect an adjustment of the blades. y

According to Fig. l the planetary gear 8 rotated by the gear Il on the propeller hub l is coaxially connected with a' bevel gear I6 meshing with'the bevel gears I2 and Il which as shown in Fig. 2 are in axial alinement with each other. 'Ihe bevel gear Il is a part of a centrifugal regulator provided with two pivotally mounted weights 20' which strive through the action of centrifugal force to axially displace a rod 2| and to opPGse the action of springs `2,2, 23 or the like. The ends of the two bevel gears Il, Il which face each other are provided with suitable clutch teeth which alternately may be brought in engagement with corresponding teeth on a slidable shaft 24. This shaft 424 extends axially slidable through the bevel gear I9 but is angularly locked t0 the endless screw 2l, the latter meshing with the worm-wheel 2B which is integral` with a shaft on which the pinion I4 is xedly secured which drives the plate I2.-

v The axial engaging movement of the shaft 24 to effect a rotation of the screw 2l is obtained through the action of two electromagnets 21, 211, whose armatures are connected with the shaft 24 by means of the linkage 2|, 29, 3l. Depending4 is co-axial with the worm gear 26. On the body of said gear Si are disposed two sectors of a circular rim I8, 31 (Fig. 2) and a complete circular rim 28 made of electrically conductive material; the said sectors are mutually vinsulated fromv` each other and are also insulated from the body of said wheel 2l. Suitable contact brushes VIl. aflixedtotherear coverofthecasingcontaining the. part o f the pilot-lakes`v the worm gear 26 and associated gears are in engagement respectively with the three abovementioned sectors. Furthermore the said contact brushes are connected to conductors 39, 40, 4I. In addition thereto a contact brush 42 is provided which engages the ring 38 and by sweeping over same may electrically connect this ring 38 with the sector 31 or with the sector 36. In the position of the brush 42 as indicated in Fig. 2, it leaves the sectors 38, 31 and 36 insulated from each other. The brush 42 is caused to rotate, for instance, by the worm gear 2E through the medium of suitable transmission gearing 43.

It will be clear that through the manipulation of the handle 3| the angular position of the sectors is varied, thereby permitting the connection of the ring 38 with either of the sectors 31 or 36, which connection takeskplace by means of the brush 42. In the first instance the electromagnet 21 will be excited and then there will be brought about the mechanical coupling of the screw 25 and shaft 24 with the bevel gear id, the pitch of the blades being thus varied in one direction until the brush 42 has been returned to its initial position illustrated in Fig, 2. In this initial position the current is interrupted, the mechanical coupling with bevel gear i8 is disconnected and the blade movement stopped.

In the second instance, however, when a contact is established between the ring 38 and the sect ir 36 the electromagnet 211 will be excited and the pitch variation will occur in a direction opposed to the preceding one, untilas stated abovethe brush 42 'is brought into its initial position in which the three elements 36, 31, 33 are disconnected from each other.

Furthermore, the gearing I8 has radially disposed around its circumference and in suitable locations, corresponding to the minimum and maximum pitch position, two teeth 44, which during the rotation thereof, proceed to strike against a lateral arm 45 of the lever 30, thereby causing a disengagement of the shaft 24 from the bevel gears I8 or I9' as the case may be independently of the electric circuit.

The centrifugal governor controls an electric switch 46 which establishes, in case of propeller speeds which are below a predetermined maximum, a contact between the conductor lead 4l coming from the battery and the conductor lead wire 4| connected to the ring 38. When the rotative speed of the propeller reaches the speed there will automatically be re-established the` speed rate for which the centrifugal governor is adjusted under which condition the contact between the conductor leads 41 and 40 will be broken and a further 'adjustment of the blade will stop.

In order to prevent incomplete and uncertain contacts and a. sparking between the switci" ontacts resulting from such faulty contain., the switch lever d@ is so pre-disposed as to have enD pertaining spring. retraction organs d2 or the like, whose operation is schematically represented in the Figure 2.

According to the diagram illustrated in Fig. 3 the functioning of the switch actuated by the centrifugal governor is identical with that yalready described; but this diagram illustrates additionally a variation consisting solely in the direct control of the electromagnets 21 and 211 by means of a switch 48 without the employment of the contact brush 42:; -Whenthe electromagvnets 21 or 211 are -being excited by means of the switch 48 an increase or a decrease of the pitch of the propeller blade is thus brought about. Upon each occurrence of a pitchadjustment, the electromagnet 49 closes a circuit energising 'a small tell-.tale lamp 50 'or some other signal. The electric circuit furthermore includes a disengaging mechanism which interrupts the circuit as often as the propeller blades attain their predetermined extreme angular position.

Having now particularly described and ascertained the nature of my said invention and in what manner the same'is to be performed, I declare that what I claim is;

l. In a controllable pitch propeller, the combination of a casing, a propeller shaft rotatably supported by said casing, a hub on said shaft,

variable pitch blades mounted in said hub, a, gear- V ing mounted on said hub for rotating the blades to change their pitch, a housing xedly attached to said casing, a centrifugal governor in said housing, means for drivingly connecting the pro` peller shaft with said centrifugal governor, said housing also containing two electromagnets for controllingv the pitch varying operation of said gearing, a gearing within said housing and in geared connection with said pitch varying gearing on said hub, coupling means operated by said electromagnets for connecting the drive connection which operates the centrifugal governor with` the gearing in said housing, and means forming electric circuits for energising said electromagnets, said means including a switch controlled by said centrifugal governor which at a speed below a predetermined speed closes said switch to energise one of said two electromagnets and which at a speed above said predetermined speed energises the other electromagnet, whereby the former operates said coupling means to effect an operation of the gearing in said housing in one direction, while the other electromagnet, when energised, operates said coupling means to cause a rotation of said last named gearing in the opposite direction, thus causing an automatic adjustment of the propeller blades lrst in one direction and upon an excess increase in speed in the OPPO- site direction until said switch is maintained open by said centrifugal governor.

2. In a controllable pitch propeller, the combination of a casing. a propeller shaft rotatably supported by said casing, a hub on said shaft, variable pitch blades mounted in said hub, a gearing mounted on said hub for rotating the blades to change their pitch, a housing xedly attached to said casing, a centrifugal governor in said housing, means for drivingly connecting the pro peller shaft with said centrifugal governor, said housing also containing two electromagnets for controlling the pitch varying operation of said gearing, a gearing within vsaid housing .and in geared connection with said pitch varying gearing on said hub, coupling means operated by said electromagnets for connecting the drive connection which operates the centrifugal governor with the gearing in said housingnn'eans forming electric circuits for energisirig said electromagnets, said means including a switch controlled by said centrifugal governor which at a speed below a predetermined, speed closes said switch to energise one of said two electromagnets and which at a speed above said predetermined speed energlses vthe other electromagnet, whereby the former operates said coupling meansto eifect an operation of the gearing in said housing in one direction, while the other electromagnet,when energised, operates said coupling means to cause a rotation of said last named gearing in the opposite direction, thus causing an automatic adjustment of the propeller blades first in one direction and upon an excs increase in speed in the opposite direction until said switch is maintained open by said centrifugal governor, and manually operable means for selectively energising said elec- -tromagnets independently of the switch cony in said housing, means for drivingly connectingthe propeller shaft with said centrifugal governor, vsaid housing also containing two electromagnets for controlling -the pitch varying operation of said gearing, a gearing within said housing and in geared connection with said pitch varying gearing on said hub, coupling means operated by said electromagnets for connecting the drive connection which operates the centrifugal governor with the gearing in said housing, means forming electric circuits for energising said electromagnets, said means including a switch controlled by said centrifugal governor which at a speed below a predetermined speed closes said switch to energise one of said two electromagnets and which at a speed above said predetermined Speed energises the other electromagnet, which the former operates said coupling means to effect an operation of the gearing in said housing in one direction, while the other electromagnet, when energised, operates said coupling means to cause a rotation of said last named gearing in the opposite direction, thus causing an'automatic advjustment of the propeller blades rst in one direction and upon an excess increase in speed in the opposite direction until said switch is mainv housing coaxial with a gear of the gearing adapt ed to be operated when said coupling means is 5, In a controllable pitch propeller, the combination of a propeller shaft, a hub on said shaft,

variable pitch blades mounted in said hub, means/ on said hub for rotating thel blades to kchange their pitch, a casing in which said propeller shaft, is supported, a housing attached to said casing, a centrifugal governor in said housing, a gearing connecting said propeller shaft with said centrifugal governor, said gearing including a bevel v gear driven by said propeller shaft and meshing with a bevel gear on the governor, a loosely ro' tatable bevel gear in axial alinement with the bevel gear on said governor and meshing with said driven bevel gear, coupling. teeth on yboth ends of said axial alined bevel gears, said hous' ing containing also two electromagnets fo'r controlling the pitch varying means on said hub, a

worm gearing within said housing and in geared connection with said pitch varying meanson said hub, a coupling member slidably mounted between said axial alined bevel gears for selectively engaging eitherone of the coupling teeth on operative, contact elements electrically insulated on said switch plate and connected with said electact member actuated by said last named gear, whereby selectively either circuit of said electromagnets may be closed by a relative movement between said switch plate and said contact member..

pme.

I tric circuit forming means, and a, rotatable con.

4. A controllable pitch propeller as claimed in f the latter, said coupling member being drivingly connected with said Worm gearing, a linkage coni necting said electromagnets with said coupling member for controlling themovement of the latter, means forming electric circuits for enerelectromagnets and which at a speed above said predetermined speed energises the other electromagnet, whereby the former shifts said coupling member in engagement with the coupling teeth of one of said axiallyvalined bevel gears to effect a rotation of said worm gearing in one direction, while the other electromagnet, when energized, moves said coupling member in engagement with the coupling teeth on the other bevel gear so as to rotate said worm gearing in the `opposite direction, thus causing an automatic adjustment of the propeller blades first in one direction and upon an excess increase in speed in the opposite direction until said switch is maintained open by said centrifugal governor.

6. In a controllable pitch propeller, the combination of a propeller shaft, a hub on said shaft, f

variable pitch blades mounted in said hub, means Y on said hub for rotating the blades to change their pitch, a casing in which said propeller shaft is supported, a housing attached to said-casing,

a centrifugal governor in said housing, a gearing connecting said propeller shaft with said centrifl ugal governor, said gearing including a bevel gear driven by said propeller shaft and meshing with a bevel gear `on the governor, a loosely rotatablev l bevel gear in axial alinement with the bevel gear on saidgovernor and meshing with said driven bevel gear, coupling teeth on both ends of said P11118 member being drivinly connected with said worm gearing, a linkage connecting said electromagnets with said coupling member for controlling the movement of the latter, means forming electric circuits for energising said electromagnefs, said means including a switch controlled by said' centrifugal governor which at a speed be- I low a predetermined speed closes said switch to energise one of said two electromagnets and which at a speed above said predetermined speed energises the other electromagnet, whereby the former shifts said coupling member in engagement with the coupling teeth of one of said axially alined bevel gears to effect a rotation of said worm gearing in one direction, While the other electromagnet, when energised, moves said coupling member ir engagement with the cou.- pling teeth on the otherbevel gear so as to rotate said worm gearing in the opposite direction, thus causing an automatic adjustment of the propeller blades firstin one direction and upon an excess increase in speed in the opposite direction until said switch is maintained open by said centrifugal governor, and manually oper` able means for selectively energising said electromagnets independently of the switch controlled by said centrifugal go Jernor to vary thereby the pitch of the propeller blades.

7. In a controllable pitch propeller, the combination of a propeller shaft, a hub on said shaft, variable pitch blades mounted in said hub, means on said hub for rotating the blades to change their pitch, a casing in which said propeller shaft is supported, a housing attached to said casing, a centrifugal governor in said housing, a gearing connecting said propeller shaft with said centrifugal governor, said gearing including a bevel gear driven by said propeller shaft and meshing with a bevel gear on the governor, a loosely rotatable bevel gear in axial alinement with the bevel gear on said governor and meshing with said driven bevel gear, coupling teeth on both ends of said axial lined bevel gears, said housing containing also two electromagnets for controlling the pitch varying means on said hub, a worm gearing within said housing and in geared connection with said pitch varying means on said hub, a coupling member slidably mounted between said axial alined bevel gears for selectively engaging either one of the coupling teeth on the latter, said coupling member being drivingly connected with said worm gearing, a linkage connecting said electromagnets with said coupling member for controlling the movement of the latter, means forming electric circuits for energising said electromagnets, said means includinga switch controlled by said centrifugal governor which at a speed below a predetermined speed closes said switch to energise one of said two electromagnets and which at a speed above saidv predetermined speed energises the other electromagnet, whereby the-former shifts said coupling member in engagement with the coupling teeth of one of said axially alined bevelgears to effect a rotation of said worm gearing in one direction, while the other electromagnet, when energised, moves said coupling member in engagement with the coupling teeth on the other bevel gear so as to rotate said worm gearing in the opposite direction, thus causing an automatic adjustment of' the propeller blades first in one direction and upon an excessincrease in speed in the opposite direction until said switch is maintained open by said centrifugal governor, and manually operable means for selectively energising said electromagnets independently of the switch controlled by said centrifugal governor to vary thereby the pitch of the propeller blades, said manually controllable means including. a manually rotatable switch plate in axial alinement with the worm gear of saidy Worm gearing, contact elements on said switch plates and conv nected with said electric circuit forming means,

tuate in two predetermined pitch positions of thepropeller blades the electromagnetically controlled linkage which operates said -coupling member to move it positivelyinto an inoperative position and thus stop a further adjustment of the blades.

CORRADINO DASCANIO. 

